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Importance of demographic surveys and public lands for the conservation of eastern hellbenders Cryptobranchus alleganiensis alleganiensis in southeast USA
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Comparisons of recent and historic population demographic studies of eastern hellbenders Cryptobranchus alleganiensis alleganiensis have identified significant population declines and extirpations associated with habitat degradation, poor water quality and disease, leading to nomination as a candidate for listing under the Endangered Species Act. However, populations in the southern Appalachian region of the range have received less attention despite relatively high levels of watershed protection due to the establishment of federally protected National Forest and National Park public lands. These watersheds likely represent some of the best remaining available habitat, yet the lack of published studies make assessment of population stability and viability very difficult. Our objectives were to (1) conduct a capture-mark-recapture (CMR) demographic study and a point transect survey on the Hiwassee River in Tennessee which is designated a National Scenic River, and is largely contained within the Cherokee National Forest, (2) quantify the size structure of the population, (3) compare abundance, survival and recruitment with historic and contemporary hellbender populations across the range, (4) assess the importance of this population and the significance of National Forest and National Park lands in the context of hellbender population conservation in the southeastern United States. We detected all age classes present, with larval hellbenders comprising 21.5% of captures. Using a combination of static life table and CMR methods, we determined that survival rates during the first year were low (~10%), but were high (68–94%) for taggable sized hellbenders. Density of hellbenders at the study site was very high (84 taggable sized hellbenders per 100m of river) compared to recent demographic studies conducted in other regions of the range. We detected hellbenders over ~28 km of river, with a mean density of 23 taggable sized hellbenders per 100m of river, and a total population estimate of 6440 taggable hellbenders. National Forest and National Park lands are likely to continue to play a particularly important role in providing suitable habitat for hellbenders in the southern Appalachians. In fact, only six of 21 known hellbender locations in Tennessee appear to show consistent larval recruitment, all of which are located within or adjacent to National Forest or National Park land.
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Improving the Utility of Artificial Shelters for Monitoring Eastern Hellbender Salamanders (Cryptobranchus alleganienses alleganiensis)
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Artificial shelters show great promise as novel, non-invasive tools for studying
hellbenders, but their use thus far has faced several challenges. During initial trials in multiple
river networks, artificial shelters routinely became blocked by sediment and dislodged during
high stream discharge events, and were rarely used by hellbenders. We sought to determine
whether these complications could be overcome via alternative shelter design, placement, and
maintenance. Between 2013 and 2018, we deployed 438 artificial shelters of two different
designs across ten stream reaches and three rivers in the upper Tennessee River Basin. We
assessed evidence for several hypotheses, postulating broadly that the availability, stability, and
use of artificial shelters by hellbenders would depend on how shelters were constructed,
deployed, and/or maintained. We found that maintaining shelters at least once every 40 days
limited sediment blockage, and building ~ 40 kg shelters with 3-4 cm thick walls and recessed
lids improved their stability during high discharge events. Additionally, we found that
hellbenders most frequently occupied and nested in artificial shelters when they were deployed
in deeper (~50+ cm) portions of reaches with high adult hellbender densities. Our results suggest
that artificial shelters can serve as effective tools for studying hellbenders when designed,
deployed, and maintained with these advancements, but also highlight some limitations of their
use.
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Artificial Nest Box Research
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Landscape Partnership Learning Network
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Self-paced virtual tutorials and classes available for practitioners and producers/landowners. The Learning Network is designed to help conservation partners, managers, and landowners learn how to use and adapt resources and tools and plan on-the-ground conservation. Once courses are completed, users can work with Landscape Partnership staff directly to discuss how to incorporate these products in their own efforts.
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Learn All About Hellbenders and Take a Tour
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Do you know what a hellbender is or where they can be found? This live session will answer those questions for you, show you what they look like by taking you on a virtual tour, share where they live, what they like to eat and who their predators are.
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Movement and Habitat Use of Eastern Hellbenders (Cryptobranchus alleganiensis alleganiensis) Following Population Augmentation
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With amphibian declines at crisis levels, translocations, including population augmentations, are commonly used for amphibian conservation. Eastern Hellbenders (Cryptobranchus alleganiensis alleganiensis) have declined to low densities in many areas of their range, making them ideal candidates for population augmentation. Both wild adults and captive-reared juveniles have been used for augmentations, but their suitability has never been directly compared. Herein, we use radio telemetry with Eastern Hellbenders to examine patterns of site fidelity, movement, and habitat use over a 2-yr period for adult residents, wild adult translocates, and captive-reared juvenile translocates. We used generalized linear models and generalized linear mixed models to identify temporal trends and explore the effects of residential status (resident vs. translocate) and origin/age (captive-reared juveniles vs. wild adults) on various ecological and behavioral traits relating to habitat. Site fidelity was high in adult residents and wild adult translocates, but lower in captive-reared juvenile translocates. Both adult and juvenile translocates had greater mean movement distances than residents, leading to larger home range sizes, but these differences decreased over time. Wild adult translocates had a higher probability of using artificial nest rocks than adult residents or captive-reared juvenile translocates. This pattern was most prevalent early in the study, indicating these shelters are particularly useful during the transition to release sites. Captive-reared juvenile translocates had lower site fidelity and utilized suboptimal habitat (smaller and fewer shelter rocks) compared to wild adults. Compared to previous studies, translocations had fewer negative effects on site residents or wild translocates and might be effective at promoting growth of Hellbender populations. However, translocations of captive-reared juveniles were less successful. As we are uncertain whether captive-rearing or ontogeny led to these differences, both longer head-starting times and conditioning should be explored to improve outcomes in captive-reared juvenile cohorts.
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Peer-reviewed Science
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Movement and habitat use of Eastern hellbenders (Cryptobranchus alleganiensis alleganiensis) following population augmentation
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With amphibian declines at crisis levels, translocations, including population augmentations, are commonly used for amphibian conservation. Eastern Hellbenders (Cryptobranchus alleganiensis alleganiensis) have declined to low densities in many areas of their range, making them ideal candidates for population augmentation. Both wild adults and captive-reared juveniles have been used for augmentations, but their suitability has never been directly compared. Herein, we use radio telemetry with Eastern Hellbenders to examine patterns of site fidelity, movement, and habitat use over a 2-yr period for adult residents, wild adult translocates, and captive-reared juvenile translocates. We used generalized linear models and generalized linear mixed models to identify temporal trends and explore the effects of residential status (resident vs. translocate) and origin/age (captive-reared juveniles vs. wild adults) on various ecological and behavioral traits relating to habitat. Site fidelity was high in adult residents and wild adult translocates, but lower in captive-reared juvenile translocates. Both adult and juvenile translocates had greater mean movement distances than residents, leading to larger home range sizes, but these differences decreased over time. Wild adult translocates had a higher probability of using artificial nest rocks than adult residents or captive-reared juvenile translocates. This pattern was most prevalent early in the study, indicating these shelters are particularly useful during the transition to release sites. Captive-reared juvenile translocates had lower site fidelity and utilized suboptimal habitat (smaller and fewer shelter rocks) compared to wild adults. Compared to previous studies, translocations had fewer negative effects on site residents or wild translocates and might be effective at promoting growth of Hellbender populations. However, translocations of captive-reared juveniles were less successful. As we are uncertain whether captive-rearing or ontogeny led to these differences, both longer head-starting times and conditioning should be explored to improve outcomes in captive-reared juvenile cohorts.
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Artificial Nest Box Research
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National Fish and Wildlife Foundation Awards $1.3 Million in Grants to Conserve Habitat in the Southeast’s Cumberland Plateau
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Seven projects will preserve forest and stream habitats, benefiting game species, forest-dependent birds, and fish and mussel species
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Eastern Hellbender News
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National Fish and Wildlife Foundation Central Appalachia Habitat Stewardship Program Announces Funding for Projects to Support Hellbender Conservation
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The National Fish and Wildlife Foundation has has announced grant awards for the 2022 cycle of its Central Appalachia Habitat Stewardship Program and several of the awards will benefit Eastern hellbenders.
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Eastern Hellbender News
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Noninvasive Method for a Statewide Survey of Eastern Hellbenders Cryptobranchus alleganiensis Using Environmental DNA
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Traditional survey methods of aquatic organisms may be difficult, lengthy, and destructive to the habitat. Some methods are invasive and can be harmful to the target species. The use of environmental DNA (eDNA) has proven to be effective at detecting low population density aquatic macroorganisms. This study refined the technique to support statewide surveys. Hellbender presence was identified by using hellbender specific primers (cytochrome b gene) to detect eDNA in water samples collected at rivers, streams and creeks in Ohio and Kentucky with historical accounts of the imperiled eastern hellbender (Cryptobranchus a. alleganiensis). Two sampling protocols are described; both significantly reduced the amount of water required for collection from the previously described 6 L collection. Two-liter samples were adequate to detect hellbender presence in natural waterways where hellbenders have been previously surveyed in both Ohio and Kentucky—1 L samples were not reliable. DNA extracted from 3 L of water collected onto multiple filters (1 L/filter) could be combined and concentrated through ethanol precipitation, supporting amplification of hellbender DNA and dramatically reducing the filtration time. This method improves the efficiency and welfare implications of sampling methods for reclusive aquatic species of low population density for statewide surveys that involve collecting from multiple watersheds.
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NRCS Staff Support the Hellbender WLFW Program by Learning About Natural Design Principles
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NRCS staff from four states met in Western NC to tour stream restoration projects for hellbenders and get a close up look at best practices.
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